Stabilized solvent

ABSTRACT

There is provided a composition of 1,1,1-trichloroethane which has as stabilizer therefor an alkyl or alkoxyalkyl ester of nitric acid which contains less than 5 carbon atoms per molecule and mixtures thereof. The stabilizer may be in the amount of 0.5 to 10 percent by weight of the 1,1,1-trichloroethane. Additional stabilizers may be included in the composition, among which are acrylonitrile and butene oxides.

United States Patent [50] Field of Search 252/171, 172,153,401, 405,364; 106/311;260/652.5

[56] References Cited UNITED STATES PATENTS 2,436,772 2/1948 Klabunde252/ I 71 3,060,125 10/1962 Sims 252/171 3,265,747 8/1966 Cormany et al.252/ 1 71 Primary Examiner-Leon D, Rosdol Assistant Examiner-William E.Schulz Attorney-Cushman, Darby and Cushman ABSTRACT: There is provided acomposition of 1,1,1- trichloroethane which has as stabilizer thereforan alkyl or alkoxyalkyl ester of nitric acid which contains less than 5carbon atoms per molecule and mixtures thereof. The stabilizer may be inthe amount of 0.5 to 10 percent by weight of the 1,1,1- trichloroethane.Additional stabilizers may be included in the cbmposition, among whichare acrylonitrile and butene oxides.

STABllLllZElD SOLVENT This is a continuation-in-part of US. applicationSer. No. 459,880, filed on May 28, 1965, which application was continuedas application Ser. No. 852,522, now abandoned.

Chlorinated hydrocarbons are widely used as solvents for metaldegreasing operations, and a variety of stabilizers have been proposedfor use in preventing decomposition of the solvent and corrosion ofmetals in contact with the solvent. 1,1,1- trichloroethane is veryefiective and safe for many applications, for example for the removal ofgrease from metals in the cold, but has a greater tendency to decomposein the presence of aluminum under such conditions than the commonersolvents such as trichloroethylene and tetrachloroethylene.

Consequently, many of the materials which function quite adequately asstabilizers in other solvents provide at best only short termstabilization of the 1,1,l-trichloroethane. Some metals, particularlysome aluminum alloys, are more readily attacked than others, and it isvery desirable that the solvent should be sufficiently stabilized towithstand prolonged contact with these very active metals or alloys eventhough, in use, such active metals may make up only a small proportionof the metal normally expected to be in contact with the solvent.

We have now found that efficient stabilization of the 1,1,1-trichloroethane against metal-induced decomposition can be achieved byaddition of an organic nitrate. By an organic nitrate we mean an organicester of nitric acid.

The organic nitrate may be for example an aromatic nitrate but we preferto use aliphatic nitrates. Certain aliphatic nitrates, particularlythose containing more than one nitrate group, tend to be explosive andgreat care should be exercised in the use of such compounds. We havefound that aliphatic mononitrates, namely the alkyl esters andalkoxyalkyl esters of nitric acid containing less than 5 carbon atomsper molecule, are most suitable. In particular we prefer to useisopropyl nitrate as it is easily accessible and has a suitable boilingpoint. Mixtures of the said esters of nitric acid may also be used ifdesired. The efficiency of these esters varies so that the optimumproportions are not necessarily the same for all the compounds in thegroup.

In general, proportions of the esters of nitric acid in the range 0.5 topercent and preferably 1 to 4 percent by weight of thel,l,ltrichloroethane are suitable.

Thus according to the invention we provide a 1,1,1- trichloroethanecomposition containing a member of the group consisting of alkyl estersand alkoxyalkyl esters of nitric acid which contain less than 5 carbonatoms per molecule and mixtures of the said esters as stabilizer for the1,1,1- trichloroethane in amount of 0.5-l0 percent preferably l-4percent by weight of the l ,l,1-trichloroethane.

When solvents are used cold, as is often the case with 1,1,]-trichloroethane, the accumulation of grease and dirt in the solventduring the degreasing process makes it economically desirable that thedirty solvent should be redistilled to recover valuable clean solvent.Furthermore, it is sometimes the practice to use l,l,l-trichloroethanein metal degreasing processes in which the workpieces are treated in theboiling solvent or its vapor, and it will be understood that in bothdegreasing using hot solvent, and in distillation, solvent vapor iscontinuously being liberated from a bulk of boiling liquid and mustconsequently be condensed back to the liquid state. For a stabilizer tobe suitable in industrial practice, therefore, it should not only becapable of performing its chemical stabilizing function but should alsobe such that it is not appreciably separated from thel,l,l-trichloroethane during distillation. For this reason we prefer touse alkyl esters and alkoxyalkyl esters of nitric acid whose boilingpoints at normal atmospheric pressure do not exceed 130 C. althoughhigher boiling members of this group of compounds also have somestabilizing action.

We prefer to include in the composition, in addition to the ester ofnitric acid, one or more members of one or more of the following groupsof compounds, i.e. nitriles,-ethers, alcohols, ketones, nitroalkanes,carboxylic esters and morpholines. We particularly prefer to use one ormore of the following compounds, i.e. acetonitrile, acrylonitrile,propionitrile, dimethoxyethane, isobutanol, tertiary butanol, tertiaryamyl alcohol, ethyl acetate, isopropyl acetate, ethyl methyl ketone,nitromethane and nitroethane. Especially we prefer to use a compositioncontaining one of the following groups of components.

1. An alkyl ester of nitric acid and a nitrile.

2. An alkyl ester of nitric acid and a tertiary alcohol.

3. An alkyl ester of nitric acid and a carboxylic ester.

4. An alkyl ester of nitric acid and an ether.

5. An alkyl ester of nitric acid and a nitroalkane.

6. An alkyl ester of nitric acid, a nitrile and a nitroalkane.

7. An alkyl ester of nitric acid, a nitrile and a tertiary alcohol.

8. An alkyl ester of nitric acid, a tertiary alcohol and a nitroalkane.

All the compounds mentioned are generally soluble in chlorinatedhydrocarbon solvents, and, as they generally do not react with the oil,grease and fatty compounds present on the surface of the articles whichare commonly degreased in such solvents, are therefore suitable forcontinual use as stabilizers in l,l,l-trichloroethane. We prefer to usestabilizers, other than the nitrate, whose boiling point is below C. toavoid separation of the stabilizers from the 1,1,1- trichloroethaneduring distillation; however stabilizers of higher boiling point mayalso be used.

As will be seen from the examples the addition of other stabilizers to acomposition containing an alkyl ester or an alkoxyester of nitric acidmay produce a solvent whose stability is considerably greater than couldbe expected from the stabilities produced by the two stabilizers whenused separately.

We have found that proportions of nitrile, ether, alcohol, ketone,nitroalkane, carboxylic ester, or morpholine, in the range 0.5 to 10percent and preferably in the range 0.5 to 4 percent by weight of thel,l,l-trichloroethane are suitable in combination with an organicnitrate. We also prefer to use a composition in which the combinedstabilizers represent not less than 3 percent (for most purposes notless than 4.5 percent) and not more than 10 percent by weight of the1,1,1- trichloroethane.

For effective stabilization the quantity of the ester of nitric acid andof the other component(s) to be used may be found to vary somewhataccording to the particular stabilizers employed and the particularconditions of use, for example, the particular metals to be in contactwith the solvent. Smaller amounts than those indicated may provide auseful stabilizing effect, but in commercial practice it is advisable tokeep the proportions above the minimum value given in order to providean adequate margin of safety. Proportions greater than those in theranges given may be used ifdesired, but little additional stabilizationis thereby achieved.

It must be understood that the stabilizers of the present invention mayfurthermore be used in conjunction with other conventional stabilizingsystems. For example it is known that decomposition of chlorinatedhydrocarbons can occur by hydrolysis under the influence of heat andwater and in the presence of metals such as iron or zinc with thedevelopment of acidity, and it has been proposed to inhibit this type ofdecomposition or to remove the acidity as it is formed by the use ofvarious additives, for instance neutral acid-acceptors such as epoxides.We have found that proportions of epoxide in the range 0.l to 1.0percent by weight of the 1,1,1- trichloroethane may be usedsatisfactorily in combination with the above-mentioned compositions.Suitable epoxides are the aliphatic epoxides containing 3-6 carbon atomsper molecule, particularly the isomeric butene oxides, mixtures of theseisomers as readily available commercially and epichlorohydrin.

A particularly useful composition is one which consists of 1,1,l-trichloroethane containing about 2 percent by weight of isopropylnitrate, about 2 percent by weight of acetonitrile, 0.75-1 percent byweight of nitromethane and about 0.25 percent by weight of a buteneoxide. Compositions of similar high performance under most conditions ofuse can, however, also be devised without the use of the relativelyexpensive nitromethane by employing acrylonitrile as the nitrilecomponent. In accordance with this feature of the invention weincorporate in the l,l,l-trichloroethane as stabilizers therefor 2-4percent of any alkyl ester or an alkoxyalkyl ester of nitric acidcontaining less than carbon atoms per molecule, 0.5-4 percent ofacrylonitrile and 0. l-l percent of butene oxides, all calculated on theweight of the l, l, l-trichloroethane. A preferred combination ofstabilizers within these limits comprises about 3 percent isopropylnitrate, about 2 percent acrylonitrile and about 0.25 percent buteneoxides.

To achieve even greater long-term stability or to increase the margin ofprotection against metal-induced decomposition of the solvent when theamount of acrylonitrile is kept near the lower end of the stated range,a proportion of a nitroalkane, e.g. 0.5-2 percent of nitromethane ornitroethane may still be added to the aforesaid compositions containingacrylonitrile if desired. Optionally also one or more of the otherchemical types of auxiliary stabilizers mentioned hereinbefore may beadded to these compositions containing acrylonitrile, especially one ormore of dimethoxyethane, isobutanol, tertiary amyl alcohol, isopropylacetate and ethyl methyl ketone. The most suitable proportion for eachof these auxiliary stabilizers is 0.5-4 percent of the weight of the1,1,1- trichloroethane. 0.5

Compositions according to our invention may be used as a solventparticularly in conventional degreasing and cleaning processes andapparatus and may be put to all the other conventional uses ofl,l,ltrichloroethane in which the presence of the stabilizers is notobjectionable,

The invention is illustrated but not limited by the following examplesin which the parts and percentages are by weight.

EXAMPLE 1 30 ml. of the composition under test were refluxed at atemperature of about 74 C. with 4 grams of an active aluminum alloy(specification 2 to 4 percent of copper, 3 to 6 percent of silicon, lessthan 0.8 percent of iron, less than 0.7 percent of manganese, less than0.2 percent of magnesium, zinc and nickel, remainder aluminum) with thefollowing results.

a. Unstabilized l,l,l-trichloroethane reacted immediately with evolutionof hydrochloric acid and formation of dark tarry products.

b. A solution of 3 percent of isopropyl nitrate in l, l, 1-

trichloroethane showed no sign of reaction when it had been refluxed for500 hours.

EXAMPLE 2 We have found that the following test is extremely rigorousand enables us to test the effect of stabilizers in a relatively shorttime.

A brass screw threaded into a block of Duralumin (an alloy consistingof9 l .5 percent of aluminum, 4 percent of copper, 1 percent ofmagnesium, 1 percent of iron, 1.5 percent of silicon, 1.2 percent ofmanganese and 0.25 percent of nickel), was ultrasonically irradiated ata frequency of 40 kHz. per sec. while immersed in the composition underthe test. The temperature of the composition was maintained at 30 C.throughout the test. Every 5 minutes throughout the test the screw wasunscrewed and the thread in the Duralumin block was inspected forcorrosion and for the presence of tarry products. When unstabilizedl,l,l-trichloroethane is submitted to this test tar formation occursalmost immediately. The results are shown in Table 1.

Table 1 -Continued 5 lsopropyl Nitrate 60 mins. 3 Dimethoxyethane 10mins. 3 Tertiarybutyl Alcohol l0 mins. 2 Acetonitrile 5 mins. 3lsopropyl Nitrate No reaction after 2 Dimethoxyethane minutes 3lsopropyl Nitrate No reaction after -H-2 Acetonitrile 90 minutes 3lsopropyl Nitrate No reaction after 2 Tertiarybutyl Alcohol 90 minutes 3lsopropyTNit rate No reaction after 2 Ethyl Acetate 90 minutes EXAMPLE 3The test was carried out in the same way as described in example 2. Theresults are shown in table 2.

EXAMPLE 4 A brass screw threaded into a block of Duralumin wasultrasonically irradiated at a frequency of 40 kHz. per sec. whileimmersed in the composition under test. The temperature of thecomposition was maintained at 60 C. throughout the test. Every 5 minutesthroughout the test the screw was unscrewed and the thread in theDuralumin block was inspected for corrosion and for the presence oftarry products. The results are shown in table 3.

TABLE 3 Percent of Time to Corrosion Stabilizer Stabilizer andProduction of Tar 3 lsopropyl Nitrate 10 mins. l Nitromethane 3lsopropyl Nitrate 10 mins. 2 Tcrtiarybutyl Alcohol 3 lsopropyl Nitrate 1hr. (solvent 2 Acetonitrile yellow after 2 hr.) 3 lsopropyl Nitrate Noreaction after 2 Acetonilrile 1 hour l Nitromethane 1.5 lsopropylNitrate No reaction after |.5 Acetonitrile l hour l.5 Nitromethane 2lsopropyl Nitrate No reaction after 2 Acetonitrile 1 hour l Nitromcthane2 lsopropyl Nitrate No reaction after 3 Acetonitrile 1 hour 0.5Nitromethanc l lsopropyl Nitrate No reaction after 3 Acetonitrilc l hour(but l Tcrtiaryamyl Alcohol liquid turbid) 2 lsopropyl Nitrate Noreaction after 2 Tertiarybutyl Alcohol 1 hour (but liquid l Nitromethaneslightly discolored EXAMPLE 5 The test was carried out in the same wayas in example 4. The results are shown in table 4.

TABLE 4 Percent of Stabilizer Time to Corrosion Stabilizer andProduction of Tar 50 mins.

1 hr. no reaction 25 mins.

1 hr. slight reaction and discoloration of solvent 30 mins.

1 hr. slight reaction and discoloration of solvent 5 mins.

EXAMPLES 6-14 For each example the following test of stability wascarried out to simulate the severe conditions which can occur in aliquor-vapor degreasing plant.

250 m/. of l,l,l-trichloroethane containing stabilizers as shown in thefollowing table 5 were placed in a 500-ml. conical flask together withg. of iron filings, l g. of aluminum swarf and three strips each 3" 0.5"of copper, mild steel and aluminum and alloy respectively. The flask wassurmounted by a soxhlet extractor modified so as to retain a constanthead of liquid above the flask and carrying above it a reflux condenser.50 ml. of the same stabilized 1,1,l-tricholoroethane were placed in theextractor together with strips of copper, mild steel and aluminum alloyas in the flask, the strips being arranged so as to lie partly in theliquid solvent and partly in the vapor space. The flask was heated sothat the solvent boiled continuously and condensate from the refluxcondenser returned continuously to the flask by way of the soxhletextractor, overflowing from the pool of liquid therein.

When unstabilized l,l,l-trichloroethane is submitted to this test itreacts almost immediately both in the flask and in the extractor andforms tarry products. The results with various stabilizer combinationspresent are shown in table 5, wherein is recorded the duration of eachtest, the amount of acidity and chloride ion produced in the solvent andthe appearance of the solvent and the metal strips at the end ofthetest.

Example 7 shows the excellent performance in this test of thethree-component stabilizer system in which the auxiliary stabilizeragainst metal-induced decomposition is acrylonitrile at the preferredconcentration of 2 percent. Examples 8-14 show results in short termtests for the same combination when the acrylonitrile is reduced to 1percent or 0.5 percent, both with and without the addition of otherauxiliary stabilizers. ln examples l3 and 14 the amount of the mainstabilizer, isopropyl nitrate was also reduced.

EXAMPLE l5 The ultrasonic irradiation test of example 2 (at 30 C.) andexample 4 (at 60 C.) was repeated on the stabilized compositions ofexamples 6 and 7. l,l,l-trichloroethane stabilized by the addition of 3percent isopropyl nitrate, 2 percent acrylonitrile and 0.25 percentbutene performed excellently at 30 C., negligible reaction beingapparent. but some reaction occurred after 15 minutes at 60 C. Incomparison, -l,l,ltrichloroethane stabilized by the addition of 2percent isopropyl nitrate, 2 percent acetonitrile, 0.75 percentnitromethane and 0.25 percent butene oxide showed negligible tarformation at both 30 C. and 60 C. This demonstrates the advantage ofincluding a proportion of the nitroalkane in the composition when thestabilized solvent is to be used under the very severe conditions ofultrasonic degreasing at high temperature.

EXAMPLES 16-18 250 ml. of l,l,l-trichloroethane containing stabilizersas shown in the following table 6 were placed in a conical flasktogether with 1 ml. of water and strips of copper, aluminum and mildsteel. The liquid in the flask was boiled for 2 days under a refluxcondenser and was then tested for its residual ability to neutralizeacid (the acid acceptance value) and for the amount of chloride ionformed. The appearance of the metal strips was also recorded. Theresults are shown in table 6. The acid acceptance value is calculated bystirring the solvent vigorously with a measured and excess amount ofhydrochloric acid and then back-titrating to neutrality. The acidacceptance value is then expressed as equivalent alkalinity of thesolvent calculated as percent NaOH in weight. The acid acceptance valuebefore the test was 0.l0for all examples.

TABLE 6 Acid accept- Chloride Example ance Appearance of ion No.Stabillsers value metal strips. produced 16 2% isopropyl nitrate. 008Three metals Not de- 2% acetonitrile. slightly tectable. 0.75%nitromethane. spotted. 0.25% butane oxide.

17 3% isopropyl nitrate. 0.08 do D0.

2% acrylonitrile. 0.25% butene oxide.

18 3% isopropyl nitrate. 0.07 Dulled and Do. 1% acrylonitrile. spotted.1% ethyl methyl ketone. 0.25% butene oxide.

EXAMPLES l9 and 20 An aluminum sheet was immersed in cold l,1,l-

TABLE 7 Example No. Stabilizers Result 3% isopropyl nitrate l9 2%acrylonitrile 0.25% butene oxide No decomposition after 24 hours 2%isopropyl nitrate 2% acetonitrile 20 0.75% nitromethane 0.25% butcneoxide No decomposition after 24 hours what we claim is:

1. A l,l,l-trichloroethane composition consisting essentially ofl,l,l-trichloroethane and a member of the group consisting of alkylesters and alkoxy-alkyl esters of nitric acid which contain less than 5carbon atoms per molecule and mixtures of the said esters as stabilizerfor the 1,1,1- trichloroethane in amount of 0.5-l0 percent by weight ofthe l, l l -trichloroethane.

2. A composition as claimed in claim 1 wherein the ester has a boilingpoint at normal atmospheric pressure which does not exceed C.

3. A composition as claimed in claim 1 wherein the ester is isopropylnitrate.

4. A composition as claimed in claim 1 wherein the ester is selectedfrom the group consisting of methyl nitrate, ethyl nitrate and2-ethoxyethyl nitrate.

5. A composition as claimed in claim 1 wherein the amount of said estersis l to 4 percent by weight of the 1,1,1- trichloroethane.

6. A composition as claimed in claim 1 wherein said compositionadditionally contains from about 0.5 to percent of the weight of thel,l,l-trichloroethane of one or more members selected from the groupconsisting of acetonitrile, acrylonitrile, propionitrile,dimethoxyethane, isobutanol, tertiary butanol, tertiary amyl alcohol,ethyl acetate, isopropyl acetate, ethyl methyl ketone, nitromethane andnitroethane.

7. A composition as claimed in claim 6 wherein the proportion of thesaid members is within the range of 0.5 to 4 percent by weight of the1,1 l-trichloroethane.

8. A composition as claimed in claim 6 wherein the combined componentsother than l,l,l-trichloroethane represent 'more than 4.5 percent andless than l0 percent by weight of the l, l l -trichloroethane.

9. A composition as claimed in claim 1 wherein the composition contains0.1 to 2 percent of the weight of the l,l,ltrichloroethane of aliphaticepoxides containing 3-6 carbon atoms per molecule.

10. A composition as claimed in claim 1 wherein the composition contains0.1 to 1 percent of the weight of the l,l,ltrichloroethane of one of theisomeric butene oxides or a mixture of the said isomers.

11. A composition as claimed in claim 1 wherein the amount of saidesters of nitric acid is 2 to 4 percent by weight of thel,l,l-trichloroethane and which contains additionally 0.5 to 4 percentof acrylonitrile and 0.1 to 1 percent of butene oxides calculated on theweight of the 1,1 l -trichloroethane.

12. A composition as claimed in claim 11 which contains additionally 0.5to 2 percent by weight of the 1,1,1-

trichloroethane of nitromethane or nitroethane. 13. A compositionclaimed in claim 11 which contains additionally 0.5 to 4 percent byweight of the 1,1,1- trichloroethane of one or more members selectedfrom the group consisting of dimethoxyethane, isobutanol, tertiary amylalcohol, isopropyl acetate and ethyl methyl ketorte 14. A stabilizedsolvent composition which comprises 1,] ,ltrichloroethane, about 3percent of its weight of isopropyl nitrate, about 2 percent of itsweight of acrylonitrile and about 0.25 percent of its weight of buteneoxides.

15. A l,l,l-trichloroethane composition consisting essentially ofl,l,l-trichloroethane and from 0.5 to 10 percent by weight of the1,1,l-trichloroethane of an alkyl ester of nitric acid which containsless than 5 carbon atoms per molecule and from 0.5 to 10 percent byweight of the 1,1,1- trichloroethane of one or more members of the groupconsisting of acetonitrile, dimethoxyethane, tertiary butanol, ethylacetate, nitromethane and nitroethane.

16. A composition as claimed in claim 15 wherein the proportion of thesaid members is within the range 0.5 to 4 percent by weight of the 1,1,l -trichloroethane.

17 A l,l,l-trichloroethane composition consisting essentially ofl,l,l-trichloroethane and from 0.5 to 10 percent by weight of thel,l,l-trichloroethane of an alkyl ester of nitric acid which containsless than 5 carbon atoms per molecule and 0.1 to 1 percent by weight ofthe l,l,l-trichloroethane of butene oxide as stabilizers for the 1,1 l-trichloroethane.

18. A composition which consisting essentially of 1,1,1-trichloroethane, about 2 percent by weight of isopropyl nitrate. about 2percent by weight of acetonitrile, about 1 percent by weight ofnitromethane and about 0.25 percent by weight of butene oxide.

19. A composition as claimed in claim 6 wherein the composition contains0.l to 1 percent of the weight of the 1,1,1- trichloroethane ofaliphatic epoxides containing 3-6 carbon atoms per molecule.

20. A composition as claimed in claim 19 wherein the compositioncontains about 2 percent by weight of isopropyl nitrate, about 2 percentby weight of acrylonitrile, 0.75 to 1 percent by weight of nitromethaneand about 0.25 percent by weight of a butene oxide, all percentagesbeing based on the weight of the l ,1 l-trichloroethane.

2. A composition as claimed in claim 1 wherein the ester has a boilingpoint at normal atmospheric pressure which does not exceed 130* C.
 3. Acomposition as claimed in claim 1 wherein the ester is isopropylnitrate.
 4. A composition as claimed in claim 1 wherein the ester isselected from the group consisting of methyl nitrate, ethyl nitrate and2-ethoxyethyl nitrate.
 5. A composition as claimed in claim 1 whereinthe amount of said esters is 1 to 4 percent by weight of the1,1,1-trichloroethane.
 6. A composition as claimed in claim 1 whereinsaid composition additionally contains from about 0.5 to 10 percent ofthe weight of the 1,1,1-trichloroethane of one or more members selectedFrom the group consisting of acetonitrile, acrylonitrile, propionitrile,dimethoxyethane, isobutanol, tertiary butanol, tertiary amyl alcohol,ethyl acetate, isopropyl acetate, ethyl methyl ketone, nitromethane andnitroethane.
 7. A composition as claimed in claim 6 wherein theproportion of the said members is within the range of 0.5 to 4 percentby weight of the 1,1,1-trichloroethane.
 8. A composition as claimed inclaim 6 wherein the combined components other than 1,1,1-trichloroethanerepresent more than 4.5 percent and less than 10 percent by weight ofthe 1,1,1-trichloroethane.
 9. A composition as claimed in claim 1wherein the composition contains 0.1 to 2 percent of the weight of the1,1,1-trichloroethane of aliphatic epoxides containing 3-6 carbon atomsper molecule.
 10. A composition as claimed in claim 1 wherein thecomposition contains 0.1 to 1 percent of the weight of the1,1,1-trichloroethane of one of the isomeric butene oxides or a mixtureof the said isomers.
 11. A composition as claimed in claim 1 wherein theamount of said esters of nitric acid is 2 to 4 percent by weight of the1, 1,1-trichloroethane and which contains additionally 0.5 to 4 percentof acrylonitrile and 0.1 to 1 percent of butene oxides calculated on theweight of the 1,1,1-trichloroethane.
 12. A composition as claimed inclaim 11 which contains additionally 0.5 to 2 percent by weight of the1,1,1-trichloroethane of nitromethane or nitroethane.
 13. A compositionclaimed in claim 11 which contains additionally 0.5 % to 4 percent byweight of the 1,1,1-trichloroethane of one or more members selected fromthe group consisting of dimethoxyethane, isobutanol, tertiary amylalcohol, isopropyl acetate and ethyl methyl ketone.
 14. A stabilizedsolvent composition which comprises 1,1,1-trichloroethane, about 3percent of its weight of isopropyl nitrate, about 2 percent of itsweight of acrylonitrile and about 0.25 percent of its weight of buteneoxides.
 15. A 1,1,1-trichloroethane composition consisting essentiallyof 1,1,1-trichloroethane and from 0.5 to 10 percent by weight of the1,1,1-trichloroethane of an alkyl ester of nitric acid which containsless than 5 carbon atoms per molecule and from 0.5 to 10 percent byweight of the 1,1,1-trichloroethane of one or more members of the groupconsisting of acetonitrile, dimethoxyethane, tertiary butanol, ethylacetate, nitromethane and nitroethane.
 16. A composition as claimed inclaim 15 wherein the proportion of the said members is within the range0.5 to 4 percent by weight of the 1,1,1-trichloroethane.
 17. A1,1,1-trichloroethane composition consisting essentially of1,1,1-trichloroethane and from 0.5 to 10 percent by weight of the1,1,1-trichloroethane of an alkyl ester of nitric acid which containsless than 5 carbon atoms per molecule and 0.1 to 1 percent by weight ofthe 1,1,1-trichloroethane of butene oxide as stabilizers for the1,1,1-trichloroethane.
 18. A composition which consisting essentially of1,1,1-trichloroethane, about 2 percent by weight of isopropyl nitrate,about 2 percent by weight of acetonitrile, about 1 percent by weight ofnitromethane and about 0.25 percent by weight of butene oxide.
 19. Acomposition as claimed in claim 6 wherein the composition contains 0.1to 1 percent of the weight of the 1,1,1-trichloroethane of aliphaticepoxides containing 3-6 carbon atoms per molecule.
 20. A composition asclaimed in claim 19 wherein the composition contains about 2 percent byweight of isopropyl nitrate, about 2 percent by weight of acrylonitrile,0.75 to 1 percent by weight of niTromethane and about 0.25 percent byweight of a butene oxide, all percentages being based on the weight ofthe 1,1,1-trichloroethane.